Transcriptional regulator AflR on the overall regulation mechanism of Aspergillus flavus

Objective: Aspergillus flavus aflR, a gene encoding a Zn(II)2Cys6 DNA-binding domain, is an important transcriptional regulator of the aflatoxin biosynthesis gene cluster. Our previous results of GO analysis for the binding sites of AflR in A. flavus suggest that AflR may play an integrative regulatory role. This study aimed to investigate the integrative function of the aflR gene in A. flavus. Design: In this study, we used Aspergillus flavus NRRL3357 as a wild-type strain (WT) and constructed a knockout strain of A. flavus ?aflR by homologous recombination. Based on the transcriptomics technology, we investigated the metabolic effects of aflR gene on growth, development and toxin synthesis of A. flavus, and discussed the overall regulation mechanism of aflR gene on A. flavus at the transcriptional level. Results: The disruption of aflR severely affected the aflatoxin biosynthetic pathway, resulting in a significant decrease in aflatoxin production. In addition, disrupted strains of the aflR gene produced relatively sparse conidia and a very small number of sclerotia. However, the biosynthesis of cyclopiazonic acid (CPA) was not affected by aflR gene disruption. Transcriptomic analysis of the ?aflR strain grown on potato dextrose agar (PDA) plates at 0 h, 24 h, and 72 h showed that expression of clustering genes involved in the biosynthesis of aflatoxin was significantly down-regulated. Meanwhile, the ?aflR strain showed significant expression differences in genes involved in spore germination, sclerotial development, and carbohydrate metabolism compared to the WT strain. Conclusions: The results showed that the A. flavus aflR gene also played a positive role in the growth and development of fungi. Overall design: mRNA profiles of wild-type (WT) and aflR knockout A. flavus at 0 h, 24 h and 72 h